java网络学习之 FtpClient 源码解析（8）

jdk 自带的ftpclient 源码解析
sun.net.ftp.FtpClient

1 首先是 create 方法： 构造FtpClient 对象

public static FtpClient create() {
    FtpClientProvider var0 = FtpClientProvider.provider();
    return var0.createFtpClient();
}

public static FtpClient create(InetSocketAddress var0) throws FtpProtocolException, IOException {
    FtpClient var1 = create();
    if (var0 != null) {
        var1.connect(var0);
    }

    return var1;
}

public static FtpClient create(String var0) throws FtpProtocolException, IOException {
    return create(new InetSocketAddress(var0, 21));
}

2 如果创建FtpClient对象的时候参数里有 host 和port 则会默认调用connect （InetSocketAddress v）方法：

如果没有，则需要客户端主动调用connect 方法

connect 方法做的事情就是创建一个socket 连接，并初始化inputstream 和outputstream 对象

public sun.net.ftp.FtpClient connect(SocketAddress var1) throws FtpProtocolException, IOException {
    return this.connect(var1, -1);
}

public sun.net.ftp.FtpClient connect(SocketAddress var1, int var2) throws FtpProtocolException, IOException {
    if (!(var1 instanceof InetSocketAddress)) {
        throw new IllegalArgumentException("Wrong address type");
    } else {
        this.serverAddr = (InetSocketAddress)var1;
        this.tryConnect(this.serverAddr, var2);
        if (!this.readReply()) {
            throw new FtpProtocolException("Welcome message: " + this.getResponseString(), this.lastReplyCode);
        } else {
            this.welcomeMsg = this.getResponseString().substring(4);
            return this;
        }
    }
}

--------------------

private void tryConnect(InetSocketAddress var1, int var2) throws IOException {
    if (this.isConnected()) {
        this.disconnect();
    }

    this.server = this.doConnect(var1, var2);

    try {
        this.out = new PrintStream(new BufferedOutputStream(this.server.getOutputStream()), true, encoding);
    } catch (UnsupportedEncodingException var4) {
        throw new InternalError(encoding + "encoding not found", var4);
    }

    this.in = new BufferedInputStream(this.server.getInputStream());
}

---------------

private Socket doConnect(InetSocketAddress var1, int var2) throws IOException {
    Socket var3;
    if (this.proxy != null) {
        if (this.proxy.type() == Type.SOCKS) {
            var3 = (Socket)AccessController.doPrivileged(new PrivilegedAction<Socket>() {
                public Socket run() {
                    return new Socket(FtpClient.this.proxy);
                }
            });
        } else {
            var3 = new Socket(Proxy.NO_PROXY);
        }
    } else {
        var3 = new Socket();
    }

    if (var2 >= 0) {
        var3.connect(var1, var2);
    } else if (this.connectTimeout >= 0) {
        var3.connect(var1, this.connectTimeout);
    } else if (defaultConnectTimeout > 0) {
        var3.connect(var1, defaultConnectTimeout);
    } else {
        var3.connect(var1);
    }

    if (this.readTimeout >= 0) {
        var3.setSoTimeout(this.readTimeout);
    } else if (defaultSoTimeout > 0) {
        var3.setSoTimeout(defaultSoTimeout);
    }

    return var3;
}

 

3 然后是登录操作：

public sun.net.ftp.FtpClient login(String var1, char[] var2) throws FtpProtocolException, IOException {
    if (!this.isConnected()) {
        throw new FtpProtocolException("Not connected yet", FtpReplyCode.BAD_SEQUENCE);
    } else if (var1 != null && var1.length() != 0) {
        this.tryLogin(var1, var2);
        StringBuffer var4 = new StringBuffer();

        for(int var5 = 0; var5 < this.serverResponse.size(); ++var5) {
            String var3 = (String)this.serverResponse.elementAt(var5);
            if (var3 != null) {
                if (var3.length() >= 4 && var3.startsWith("230")) {
                    var3 = var3.substring(4);
                }

                var4.append(var3);
            }
        }

        this.welcomeMsg = var4.toString();
        this.loggedIn = true;
        return this;
    } else {
        throw new IllegalArgumentException("User name can't be null or empty");
    }
}

public sun.net.ftp.FtpClient login(String var1, char[] var2, String var3) throws FtpProtocolException, IOException {
    if (!this.isConnected()) {
        throw new FtpProtocolException("Not connected yet", FtpReplyCode.BAD_SEQUENCE);
    } else if (var1 != null && var1.length() != 0) {
        this.tryLogin(var1, var2);
        if (this.lastReplyCode == FtpReplyCode.NEED_ACCOUNT) {
            this.issueCommandCheck("ACCT " + var3);
        }

        StringBuffer var4 = new StringBuffer();
        if (this.serverResponse != null) {
            Iterator var5 = this.serverResponse.iterator();

            while(var5.hasNext()) {
                String var6 = (String)var5.next();
                if (var6 != null) {
                    if (var6.length() >= 4 && var6.startsWith("230")) {
                        var6 = var6.substring(4);
                    }

                    var4.append(var6);
                }
            }
        }

        this.welcomeMsg = var4.toString();
        this.loggedIn = true;
        return this;
    } else {
        throw new IllegalArgumentException("User name can't be null or empty");
    }
}

------------

可以看到这个方法先发送了一个USER命令  ，发现需要密码，有发送了一个 PASS 命令

private void tryLogin(String var1, char[] var2) throws FtpProtocolException, IOException {
    this.issueCommandCheck("USER " + var1);
    if (this.lastReplyCode == FtpReplyCode.NEED_PASSWORD && var2 != null && var2.length > 0) {
        this.issueCommandCheck("PASS " + String.valueOf(var2));
    }
}

4 用户登录成功之后可以进行其他操作

首先设置一些 属性

然后可以切换目录

还可以上传文件

 

下载文件

查看文件列表

 

删除目录 删除文件,重命名文件

public abstract FtpClient deleteFile(String var1) throws FtpProtocolException, IOException;

还可以获取一些配置信息，文件信息或者连接信息

 

 

5 上传文件的源码

public OutputStream putFileStream(String var1, boolean var2) throws FtpProtocolException, IOException {
    String var3 = var2 ? "STOU " : "STOR ";
    Socket var4 = this.openDataConnection(var3 + var1);
    if (var4 == null) {
        return null;
    } else {
        boolean var5 = this.type == TransferType.BINARY;
        return new TelnetOutputStream(var4.getOutputStream(), var5);
    }
}

public sun.net.ftp.FtpClient putFile(String var1, InputStream var2, boolean var3) throws FtpProtocolException, IOException {
    String var4 = var3 ? "STOU " : "STOR ";
    short var5 = 1500;
    if (this.type == TransferType.BINARY) {
        Socket var6 = this.openDataConnection(var4 + var1);
        OutputStream var7 = this.createOutputStream(var6.getOutputStream());
        byte[] var8 = new byte[var5 * 10];

        int var9;
        while((var9 = var2.read(var8)) >= 0) {
            if (var9 > 0) {
                var7.write(var8, 0, var9);
            }
        }

        var7.close();
    }

    return this.completePending();
}